£40bn Thames airport 'would be ready in just 10 years'

A huge airport could be built in the Thames estuary within 10 years, according to a new report commissioned by Boris Johnson.

Experts will this week call for the mayor to push ahead with a £40billion scheme to replace plans for a third runway at Heathrow.

The development would have four runways across two islands in the river and be linked to terminals on the mainland by either tunnels and bridges.

It would be powered by giant water turbines that rely on the energy created by the rising and falling tide.

Engineer Doug Oakervee claims the airport will be easier to build than the revolutionary Hong Kong international airport he helped to construct, which was built on a largely artificial island and opened in 1998. A report will be passed to the mayor when details are finalised in three weeks.

Mr Johnson has angered environmentalists by suggesting a Thames airport, with new high-speed railway links, could replace a third runway at Heathrow. The Royal Society for the Protection of Birds say it would be "disastrous" for the 200,000 birds in the estuary.

But Mr Johnson said a Thames estuary airport "has to be seriously investigated as an option for London's long-term aviation needs".

"On Wednesday Doug Oakervee, a civil engineering genius, will explain how it's easier to build an airport in the estuary than it was in Hong Kong or Singapore. Air quality in London would be completely imperilled by a third runway at Heathrow. It's environmentally nonsensical."

Although an exact location has not yet been decided, sources say Mr Oakervee believes the environmental impact will be lessened if the airport is built over two islands rather than one. Each would be 2.8miles long and 1.2miles wide, with passengers shuttled between the two in a tunnel or on bridges running from Essex on the north bank to Kent in the south.

The terminal in Kent could be linked to the new Crossrail line, so passengers could be in central London within 35 minutes. It would connect to the M2 by a new road link and a smaller terminal in Essex is also being discussed.

Building the airport has been described as "a piece of cake" by Tom Smit from the Dutch firm Royal Haskoning, which is working on plans for an island airport near Amsterdam.

It would involve sinking 60ft blocks of concrete into the riverbed to form a dyke which is then drained of water and filled with bricks. The new airport would then be built on top.

However there are fears that the adverse impact on the flow of the Thames could lead to erosion, flooding and the loss of marine habitats.

The RSPB said: "An airport in the Thames estuary is a complete non-starter ecologically, environmentally and economically."

The airport would also need to avoid the estuary's five shipping lanes.

Mr Johnson's plans have not yet won public backing from David Cameron. But Labour MP and former planning minister Nick Raynsford has said he would support an estuary airport and admitted growing unease in the Labour ranks over a third Heathrow runway.